警告：socket_recv（）：无法从套接字[0]读取：操作完成

Question

I have five clients connected to my php socket, with html5 javascript.

Sometimes the php socket gives this error, and doubles the messages to the clients, for some strange reason:

Warning: socket_recv(): unable to read from socket [0]:  Operation complete

How can I fix this trouble?

This is the full code:

<?php

$host = '192.168.0.201'; //host
$port = '9000'; //port
$null = NULL; //null var
//Create TCP/IP sream socket
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
//reuseable port
socket_set_option($socket, SOL_SOCKET, SO_REUSEADDR, 1);

//bind socket to specified host
socket_bind($socket, $host, $port);

//listen to port
socket_listen($socket);

//create & add listning socket to the list
$clients = array($socket);

//start endless loop, so that our script doesn't stop
while (true) {
//manage multipal connections
$changed = $clients;
//returns the socket resources in $changed array
socket_select($changed, $null, $null, 0, 10);

//check for new socket
if (in_array($socket, $changed)) {
    $socket_new = socket_accept($socket); //accpet new socket
    $clients[] = $socket_new; //add socket to client array

    $header = socket_read($socket_new, 1024); //read data sent by the socket

    perform_handshaking($header, $socket_new, $host, $port); //perform websocket handshake

    socket_getpeername($socket_new, $ip); //get ip address of connected socket
    //$response = mask(json_encode(array('type' => 'system', 'message' => $ip . ' connected'))); //prepare json data
    //send_message($response); //notify all users about new connection
    //make room for new socket
    $found_socket = array_search($socket, $changed);
    unset($changed[$found_socket]);
}

//loop through all connected sockets
foreach ($changed as $changed_socket) {

    //check for any incomming data
    while (socket_recv($changed_socket, $buf, 1024, 0) >= 1) {
                    echo $buf;


        $received_text = unmask($buf); //unmask data
        $tst_msg = json_decode($received_text); //json decode 

        $user_message = $tst_msg; //message text

        //prepare data to be sent to client
        $response_text = mask(json_encode($user_message));
        send_message($response_text); //send data
        break 2; //exist this loop
    }

    $buf = @socket_read($changed_socket, 1024, PHP_NORMAL_READ);
    if ($buf === false) { // check disconnected client
        // remove client for $clients array
        $found_socket = array_search($changed_socket, $clients);
        socket_getpeername($changed_socket, $ip);
        unset($clients[$found_socket]);

        //notify all users about disconnected connection
        //$response = mask(json_encode(array('type' => 'system', 'message' => $ip . ' disconnected')));
        //send_message($response);
    }
}
}
// close the listening socket
socket_close($sock);

function send_message($msg) {
global $clients;
foreach ($clients as $changed_socket) {
    @socket_write($changed_socket, $msg, strlen($msg));
}
return true;
}

//Unmask incoming framed message
function unmask($text) {
$length = ord($text[1]) & 127;
if ($length == 126) {
    $masks = substr($text, 4, 4);
    $data = substr($text, 8);
} elseif ($length == 127) {
    $masks = substr($text, 10, 4);
    $data = substr($text, 14);
} else {
    $masks = substr($text, 2, 4);
    $data = substr($text, 6);
}
$text = "";
for ($i = 0; $i < strlen($data); ++$i) {
    $text .= $data[$i] ^ $masks[$i % 4];
}
return $text;
}

//Encode message for transfer to client.
function mask($text) {
$b1 = 0x80 | (0x1 & 0x0f);
$length = strlen($text);

if ($length <= 125)
    $header = pack('CC', $b1, $length);
elseif ($length > 125 && $length < 65536)
    $header = pack('CCn', $b1, 126, $length);
elseif ($length >= 65536)
    $header = pack('CCNN', $b1, 127, $length);
return $header . $text;
}

//handshake new client.
function perform_handshaking($receved_header, $client_conn, $host, $port) {
$headers = array();
$lines = preg_split("/
/", $receved_header);
foreach ($lines as $line) {
    $line = chop($line);
    if (preg_match('/\A(\S+): (.*)\z/', $line, $matches)) {
        $headers[$matches[1]] = $matches[2];
    }
}

$secKey = $headers['Sec-WebSocket-Key'];
$secAccept = base64_encode(pack('H*', sha1($secKey . '258EAFA5-E914-47DA-95CA-C5AB0DC85B11')));
//hand shaking header
$upgrade = "HTTP/1.1 101 Web Socket Protocol Handshake
" .
        "Upgrade: websocket
" .
        "Connection: Upgrade
" .
        "WebSocket-Origin: $host
" .
        "WebSocket-Location: ws://$host:$port/demo/shout.php
" .
        "Sec-WebSocket-Accept:$secAccept

";
socket_write($client_conn, $upgrade, strlen($upgrade));
}

Thank you in advance.

Answer 1

this occurs when the client crash. In this situation the return of socket_recv() is false, use === operator to check. On client normal exit the return is 0.

You can simulate both situations using Putty. Once connected to your server try:

1. kill with task manager (return false)
2. Exit normally (return 0)

Always use socket_close after client close or crash